Brassica Pests: Identification (Part 1 of 2)
By Rebecca Halcomb, Leadership in Urban Agriculture Internship, Fall II 2020
I had a lot of pest issues this year, but the ones that did the most damage were the pests that took out my brassica crops of collard greens, kale, broccoli, and cabbage.
I had hand-removed a few caterpillars, but less than a week later, this was what I found when I walked out to my garden on August 14th:
These had been the largest most beautiful collard greens I’d ever grown, and were now covered in caterpillars I didn’t recognize:
When I came to intern at Urban Harvest STL, I noticed one of the same pests I had encountered on my brassicas, and learned it was called a cabbage looper. I originally thought it was just the cabbage looper in various phases that I was dealing with in my garden, but when I started researching and looked back at my garden pictures, I noticed that the caterpillars on my collard greens and kale were different from the caterpillars on my broccoli, so I was dealing with multiple pests. I decided to research both pests I had issues with, and then I also ended up finding info on another cabbageworm called the imported cabbageworm. That caterpillar looked very similar to the cabbage looper, but the butterfly was different, so I wanted to address those as well.
First let’s look at how to identify all 3 brassica-eating culprits.
Cabbage Looper ID
Here’s a picture of the cabbage looper moth to look out for.
It will lay eggs that look like this.
As a caterpillar, it will look like this.
Imported Cabbage Worm ID
The imported cabbage white butterfly to watch out for, that produces the green imported cabbage worm, looks very similar to the cabbage looper caterpillar.
Their eggs are also tiny and white, but more cone-shaped.
This is what the green cabbage worm looks like. It’s slightly fatter, doesn’t make the distinctive loop with its back when it crawls, and has a faint yellow stripe down the back.
Cross-Striped Cabbageworm ID
It took me awhile to find the name for the striped caterpillar that skeletonized my collards so badly, but I finally found my worst culprit: the cross-striped cabbageworm.
Here are some pictures of the moth to look out for, the eggs they will lay, and a better close up of the caterpillar:
The moral of this is that pest ID can sometimes be tricky, but it’s definitely worth it so you know what you’re dealing with, and the best way to manage the pest so that you can harvest as much high quality crop as possible. In Part 2, we’ll examine how to thwart our brassica foes.
Resources
University Extension websites have compiled a lot of helpful info on garden pests:
University of Minnesota Extension has pictures of the cabbage looper eggs, which are very tiny white round dots, about the size of a pinhead. There are also pictures of the dark green pellets that they excrete: https://www.vegedge.umn.edu/pest-profiles/pests/cabbage-looper
UMass and UConn Extensions have some good info on the Cross-Striped Cabbage Worm: https://ag.umass.edu/vegetable/fact-sheets/cross-striped-cabbage-worm
http://ipm.uconn.edu/documents/raw2/html/579.php?display=print
Non-Extension Resources:
This website has pictures of the various Cabbage Looper stages, their defining characteristics for accurate ID, as well as a full list of the plants they feed on, and their egg laying schedule: http://www.idtools.org/id/citrus/pests/factsheet.php?name=Cabbage+looper
This website notes the difference between the Cabbage looper and Imported cabbageworms: https://www.growveg.com/pests/us-and-canada/cabbage-worm-cabbageworm-cabbage-looper/
Some helpful info that compare the 2 cabbageworms: https://theberkshireedge.com/natures-turn-unwelcome-cabbage-white-butterflies-and-dreaded-cross-striped-cabbage-moths/
